The book portrays their father as an 'ogre' who mistreated them.
the 'ogre' of inflation
(..) you don't have any friends. Wow. Only a true friend would be that truly honest. Listen, little donkey. Take a look at me. What am I? -- - Really tall? - No! I'm an ogre. You know. ''Grab your torch and pitchforks.'' Doesn't that botheryou? Nope. - Really? - Really, really. - Oh. (..)2001 Shrek
(..) never seen a donkey fly. Ha, ha! Uh-oh. Seize him! After him! He's getting away! T T You there. Ogre! Aye? By the order of Lord Farquaad, I am authorized to place you both under arrest... and transport you to a designated... resettlement facility. Oh, really? (..)2001 Shrek